1. Field of the Invention
The present invention relates to well completion equipment, and more specifically to mechanisms for actuating downhole well tools that require pressurized hydraulic fluid to operate.
2. Description of the Related Art
It is well known that many downhole devices require power to operate, or shift from position to position in accordance with the device's intended purpose. A surface controlled subsurface safety valve (SCSSV) requires hydraulic and/or electrical energy from a source located at the surface. Setting a packer that is sealably attached to a string of production tubing requires either a tubing plug together with application of pressure on the tubing, or a separate and retrievable "setting tool" to actuate and set the packer in the tubing. Sliding sleeves or sliding "side door" devices may also require electrical power, hydraulic pressure or a combination thereof, commonly referred to as "electro-hydraulic" activation. It will become apparent to anyone of normal skill in the art that many downhole devices requiring power for actuation can be adapted to utilize this invention. Such devices may comprise: packers, such as those disclosed in U.S. Pat. Nos. 5,273,109, 5,311,938, 5,433,269, and 5,449,040; perforating equipment, such as disclosed in U.S. Pat. Nos. 5,449,039, 5,513,703, and 5,505,261; locking or unlocking devices, such as those disclosed in U.S. Pat. Nos. 5,353,877 and 5,492,173; valves, such as those disclosed in U.S. Pat. Nos. 5,394,951 and 5,503,229; gravel packs, such as those disclosed in U.S. Pat. Nos. 5,531,273 and 5,597,040; flow control devices or well remediation tools, such as those disclosed in U.S. Pat. Nos. 4,429,747, and 4,434,854; and plugs or expansion joints, of the type well known to those in the art.
Each of these well known devices has a method of actuation, or actuation mechanism that is integral and specific to the tool. Many of these devices are actuated only a few times with the expensive actuating mechanism being left unusable in the well with the tool. In virtually every case, actuating mechanisms have seals which direct energy to moving parts that perform the work desired. After its work is completed, the seal may remain in the well for many years where corrosives and stresses in the material may cause seal failure. Seal failure can cause leaks that may compromise the completion, reduce or prohibit further production from the well until such leak is repaired, and compromise the safety of operations personnel.
There is a need for a device which can provide one or more sources of pressurized hydraulic fluid into the downhole environment, enabling actuation of any number of downhole tools, and in one embodiment, be retrieved by any of several well known methods (e.g. a work string, a coiled tubing string, wireline, electric lines, etc.). The device should be adaptable for various downhole tasks in various downhole tools, and be simple to allow for redress in the field. It should also be adaptable for permanent installation in the completion, thereby allowing multiple functions to be performed on multiple tools located therein, all controlled by an operator at a control panel on the earth's surface.